quote:
Originally posted by blitz77:
BTW, in order for chance to create the simple proteins, there has to be a high enough concentration of amino acids, and for the amino acids to link up against the energy gradient, and for the probability that all of them are left-handed (which, for a 100-amino acid protein, would be 1/2^100).
Can you back up that probability calculation?
I've seen calculations like this before and they usually neglect a few factors
Like:
1) There should have been loads of energy around at the time. The planet was young and very violent-- volcanoes, etc.
2) You don't have to create a protein by chance, only a small self-replicating precursor, a catalyst. From there on the dice are loaded.
3) What is the time-frame and base volume of 'soup' used in this calculation? These reactions would have been occurring over the whole surface of the Earth for millions or hundreds of millions of years. Again, a few good molecules and the dice are loaded.
4) Several thoughts about left-handedness.
There may be a REASON for it besides chance.
from Nature magazineor:
Polarized light
Even if the above is incorrect, there may be a biochemical reason for left-handedness. I recall reading a paper suggesting that left-handed molecules function marginally better than right-handed one. Selection takes over. Sadly, I cannot find this paper.
Even if the above is incorrect, if the first proteins happened to be left-handed, they could have simple flooded the market drowning out their right-handed siblings.
Basically, things aren't as random as they appear.
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